Survival kits are made up of a number of items needed to meet certain emergency situations, such as, when one becomes lost or stranded. In those situations, a compass is one of those items which are essential to survival, and it is important that the compass as well as other items occupy a minimum of space, are extremely lightweight but are both reliable and efficient in use.
Liquid-filled compasses are becoming increasingly popular and in widespread use. Such compasses typically employ a disk supported on a bearing in a chamber containing liquid. The liquid serves to damp any tilting or rotational movement of the compass disk but at the same time the disk is free to rotate to properly orient a marker with the North magnetic pole. To this end, typically magnets are mounted on the compass disk or closely associated with the disk to cause it to be oriented when freely suspended in the liquid. However, those liquid-filled compasses which are now commercially available occupy too much space to be satisfactory for use in a survival kit. It is therefore desirable to provide for a compass disk which can be normally stored in a dry condition so as to occupy a minimum of space but when needed can be placed on a liquid surface and orient itself to provide an accurate compass reading. Further, it is desirable that the compass disk can be conveniently stored on a card no larger than a credit card and carried on one's person with instructions on the card for use of the compass when needed under emergency conditions; and for example to properly instruct one in the use of the compass disk as a liquid compass and in such a way that the compass will operate effectively with a minimum quantity of liquid or water.
Representative types of liquid-filled compasses are those set forth and described in U.S. Letters Pat. No. 4,175,333 to M. G. Kramer and owned by the assignee of this invention, and U.S. Pat. No. 4,236,316 to K. Suzuki.